COI Funded Project: Chemical and Molecular Biological Characterization of Dissolved Organic Nitrogen in the Coastal Zone


Project Duration: 6/1/98-12/31/99
Key Words: nutrient cycling, eutrophication, dissolved organic nitrogen (DON), harmful algal blooms (HAB)

Proposed Research

Coastal Zone development has dramatically increased the transfer of nutrients from the continental margin to the sea. In the past, concern has focused on nitrates, ammonia, and phosphates; inorganic forms of nutrients. However, as watersheds are developed, the amount of organic nitrogen loading increases proportionally. Dissolved organic nitrogen (DON) can contribute up to 80% of the total nutrient loading in developed watersheds. DON has been considered to be largely inert, cycling on long time scales and not contributing to coastal zone eutrophication. However, there is now good evidence that DON is utilized directly as a nutrient by some marine algae, including species which contribute to harmful algal blooms. Utilization of DON as a nutrient fundamentally changes our concepts of nutrient cycling in seawater. We do not know what DON is, or how it is used by marine algae as a nutrient. Using facilities uniquely available at WHOI, we have evidence that DON may made of specific proteins that are somehow resistant to microbiological degradation. We propose to investigate the chemical and molecular biological characteristics of DON in order to better understand its fundamental chemical properties and develop appropriate tools needed to more fully investigate its origin and fate in the marine environment.